Printing by a jet printer is a system of jetting an ink from nozzles and attaching the ink onto a recording material and since the nozzles are in a non-contact state with the recording material, good printing can be applied onto a curved surface or a surface having an uneven irregular form.
Various kinds of inks have been proposed as an ink for the jet printer. For example, JP-A-56-49772 proposes an ink containing a styrene-acrylic copolymer resin, a plasticizer, a dye, and a solvent composed of water and an alcohol and having a pH in the range of from 7.5 to 10.5 as an ink having a good adhesion to the surfaces of polyolefins or copolymers thereof, JP-A-60-110770 proposes an ink containing a styrene-acrylic acid copolymer resin having a mol ratio of the styrene monomer to the acrylic acid monomer of from 1 to 4, a dye, an evaporation retardant, and a solvent composed of an alcohol and a ketone. JP-A-62-109870 proposes an ink containing a quaternary ammonium salt as an electrically conductivity imparting agent as an ink which does not erode the metals of coating apparatus and has an excellent adhesion to a recording material attached with a wax (the term "JP-A" as used herein means an "unexamined Japanese patent application").
Also, JP-A-2-276870 proposes an ink containing a resin having a good compatibility with a wax as an ink having an excellent adhesion to a surface containing a wax.
However, the inks disclosed in foregoing JP-A-56-49772 and JP-A-60-110770 show an excellent adhesion to various recording materials but have a problem that spreading of the ink dots and the adhesion thereof are inferior to a recording material attached with a wax and a recording material coated with a coating composition containing a wax.
Also, the ink described in the foregoing JP-A-62-109870 shows an improved adhesion to a recording material attached with a wax but the adhesion is yet insufficient.
Furthermore, the ink described in the foregoing JP-A-2-276870 shows an improved adhesion to a surface containing a wax but has a problem that the adhesion and the abrasion resistance to the untreated surface of glass, a metal, a plastic, etc., are insufficient.